docs: def unpack(self, unpacker):
          """
          unpacks an exception handler entry in an exception table. Updates
          the internal structure of this instance
          """
  
          (a, b, c, d) = unpacker.unpack_struct(_HHHH)
  
          self.start_pc = a
          self.end_pc = b
          self.handler_pc = c
          self.catch_type_ref = d